This invention relates to a propellant and method, and more particularly to a propellant having a plateau or mesa burning characteristic due to the presence of at least one burning rate modifier having a particle size of up to 1 micron.
It is well known in the prior art to add certain types of finely divided additives to propellants in order to modify their performance in some way. Many different types of additives are known. It is desirable to modify high impulse propellants in order to control the burning rate thereof. However, many difficulties arise in the preparation of high impulse propellants due to their sensitivity. When the burning rate of a high impulse propellant is plotted against combustion pressure on a logarithmic graph, the resultant graph approximates a straight line. If a high impulse propellant is to be used in a rocket, the straight line indicates that the rocket nozzle must be designed carefully to avoid problems with burning rate and pressure build up. If the nozzle is not designed properly, the propellant may not burn, or the propellant may burn too fast, build up pressure, and explode. All of these features render an otherwise desirable high impulse propellant unattractive. It is desirable that, for a given pressure range, the burning rate not increase (plateau) and sometimes even decrease with increasing pressure (mesa). If a propellant is appropriately formulated to produce a plateau or mesa burning characteristic, nozzle design is not so critical in a rocket motor. In the past burning rate modifiers have not been able to effectively modify high impulse propellants when prepared by a slurry cast process as desired.